In response to the claims, South Korea sent troops to its border with the North with photos showing heavily-armed tanks and troops swarming the de-militarised zone in the hours following the alleged test.

Nations from across the globe - including traditional ally China - immediately spoke out against the test and lambasted the nation.

Britain, the United States, Japan, Germany joined a chorus of outraged voices slamming North Korea.

Prior to the test, Kim Jong-un signed his name to a report which authorised the testing of the bomb underground.

Obama to send Kim Jong-un 'strongly worded' letter

According to reports, the President of the United States is planning to send Kim Jong-un a “strongly worded” letter.

North Korea has said it tested the Hydrogen bomb in retaliation to alleged US aggression.

(Photo: Getty)

12:26

Full Russia statement

Russia’s Foreign Ministry said: “On January 6 the North Korean government announced a successful test of a hydrogen bomb.

“Russia is studying this statement closely and analysing technical information.

“If such a test can be confirmed it would represent another step by Pyongyang towards development of nuclear weapons, which would be a grave violation of international law and UN Security Council resolutions.

“Such actions are fraught with the danger of aggravating tensions on the Korean peninsula, which is already characterised by high potential for political or military confrontation.”

12:14

Inside the mad, bad world of Kim Jong-un

Smirking dictator Kim Jong-un is part psychopath and part myth in the western world - much like his father before him.

While Kim Jong-il famously claimed to have bowled a perfect game of ten pin bowling as well as a world record 38 under par golf round (which included 11 holes-in-one), his son’s fame is slightly different.

The Manchester United fan is thought to have been schooled in Switzerland and become a fan of basketball there too.

Germany 'summon' ambassador

Germany has acted quickly to let North Korea know in no uncertain terms it does not agree with the state’s nuclear weapons.

The nation’s foreign spokesman said the government had summoned the North Korean ambassador to discuss the matter.

North Korea is yet to find an ally following news of the test.

China, the secretive state’s normal ally, has joined the list of countries slamming North Korea in the wake of the alleged test.

(Photo: Getty)

11:56

Nato demand North Korea "abandon" nuclear weapons

Nato is another group to slam North Korea following news of the alleged H-bomb test.

Jens Stoltenberg, former prime minster of Norway and current chief of Nato said the rogue state must “abandon” nuclear weapons.

He said: “The nuclear weapons test announced by North Korea undermines regional and international security, and is in clear breach of UN Security Council resolutions.

“I condemn the continued development by North Korea of nuclear weapons and ballistic missile programmes and its inflammatory and threatening rhetoric.

“I call on North Korea to fully respect its international obligations and commitments.

“North Korea should abandon nuclear weapons and existing nuclear and ballistic missile programmes in a complete, verifiable and irreversible manner, and engage in credible and authentic talks on denuclearisation.”

11:52

Moscow 'extremely worried'

Moscow is “extremely worried” by reports of North Korea conducting its first test of a hydrogen bomb, Russian news agencies quoted Kremlin spokesman Dmitry Peskov as saying

“President Vladimir Putin has ordered to study thoroughly the readings of all monitoring stations, including seismological ones, and analyse the situation in case the reports about the (H-bomb) test are confirmed,” Peskov said.

(Photo: Host Photo Agency/Ria Novosti via Getty Images)

11:50

Labour condemn test "in strongest possible terms"

Hilary Benn MP, Labour’s Shadow Foreign Secretary, commenting on reports that North Korea has carried out a nuclear test, said: “There is still uncertainty about exactly what has happened but, if verified, the nuclear test carried out by North Korea represents a clear violation of numerous UN Security Council Resolutions and I condemn it in the strongest possible terms.

“The country’s nuclear programme poses a grave threat to international peace and security and does nothing to improve the prospects of the people of North Korea, who continue to pay the price for the country’s misguided policies.

“I call on the North Korean government to recognise its commitments under international law, and urge it and the international community to reinvigorate efforts towards the goal of denuclearisation of the Korean peninsula, ideally through the resumption of the Six Party Talks.”

(Photo: PA)

11:48

Japan test for radiation

Japan has sent planes to check for radiation following the alleged test.

Earlier today, Japan slammed North Korea in the wake of the news and said it would be examining whether or not there was any radiation.

China also said it would be looking into any radiation crossing the border.

11:40

'The H-bomb of justice'

The nuclear test came two days ahead of what is believed to be Kim’s birthday.

Speaking through the government’s official press agency, the North called the device the “H-bomb of justice” and said: “The U.S. is a gang of cruel robbers which has worked hard to bring even a nuclear disaster to the DPRK,” using the official acronym for North Korea.

However, the agency said Pyongyang will act as a responsible nuclear state and vowed not to use its nuclear weapons unless its sovereignty was infringed. It said it will not transfer its nuclear capabilities to other parties.

(Photo: Reuters)

11:37

Foreign Secretary

Philip Hammond met with the Chinese Premier earlier today.

The talks were scheduled before news of the test broke, but the Foreign Secretary said he raised the matter.

China has joined other nations in condemning the alleged hydrogen bomb test.

11:34

'Not a true H-Bomb'

“Given the scale, it is hard to believe this is a real hydrogen bomb,” said Yang Uk, a senior research fellow at the Korea Defence and Security Forum.

“They could have tested some middle stage kind (of device) between an A-bomb and H-bomb, but unless they come up with any clear evidence, it is difficult to trust their claim.”

Joe Cirincione, a nuclear expert who is president of Ploughshares Fund, a global security organisation, said North Korea may have mixed a hydrogen isotope in a normal atomic fission bomb.

“Because it is, in fact, hydrogen, they could claim it is a hydrogen bomb,” he said.

“But it is not a true fusion bomb capable of the massive multi-megaton yields these bombs produce”.

11:25KEY EVENT

What is a hydrogen bomb and what can it do?

A hydrogen bomb, or H-bomb, is the informal term for a thermonuclear device.

They are detonated in two stages, the first a nuclear fission reaction that then ignites a secondary nuclear fusion reaction.

Fission is another word for splitting, so the energy in a nuclear fission blast is created when the nuclei of materials like uranium or plutonium are split.

EU statement

In a statement to the press, the EU’s foreign policy chief said: “ If confirmed, this action would represent a grave violation of (North Korea’s) international obligations not to produce or test nuclear weapons, as determined by several United Nations Security Council Resolutions.

Federica Mogherini said it would also be “a threat to the peace and security of the entire Northeast Asia region.”

10:18

EU 'attacks' North Korea

The European Union has added to the voices slamming North Korea this morning.

In a statement following the alleged test, the Union said that if it was confirmed the test “Would be a grave violation of international obligations.”

So far nations including the UK, USA, Russia, Japan and China have attacked the secretive state.

(Photo: Reuters)

10:06

UK shares "tumble" over fears

UK shares stumbled on Wednesday as commodity-related companies were hit by fresh worries over weakness in China, the world’s largest consumer of metals, while North Korea’s nuclear test dented wider confidence.

The People’s Bank of China set a weaker midpoint for the yuan, and a private survey showed that activity in China’s services sector expanded at its slowest rate in 17 months in December.

The FTSE 350 Mining Index fell 2.5, with BHP Billiton, Antofagasta, Rio Tinto, Glencore and Anglo American down between 1.1 and 3.8 percent.

“We are in a new world - China’s not growing (in) double digits, demand for raw materials has fallen through the floor and it’s both a supply and demand side problem,” Mike van Dulken, head of research at Accendo Markets, said.

09:54

Russia slams North Korea

Russia has joined other nations in condemning this morning’s alleged H-Bomb test.

The nation’s foreign ministry said it would “amount to gross violation of international law” if the explosion was confirmed.

The UK, USA, Japan and China are among other world powers to come out and slam the secretive state.

(Photo: Getty)

09:52

What we know so far

North Korea this morning announced it had successfully tested a hydrogen bomb.

The secretive state made the announcement on TV and radio, claiming the test was one of a number of “eye-catching miracles”.

Hammond: "Excellent" meeting with Chinese

Foreign Secretary Philip Hammond has just tweeted after coming out of a meeting with the Chinese.

The Tory minister said he discussed the alleged H-bomb test by the North Koreans.

09:38KEY EVENT

"Thrilling sound of our first hydrogen bomb"

In another note, Kim Jong-un wrote about welcoming in the new year with the explosion.

In a peculiar note, written in the same messy handwriting, the portly dictator told his nation now was a time to celebrate.

He wrote: “Let’s begin the year of 2016 ... with the thrilling sound of our first hydrogen bomb explosion, so that the whole world will look up to our socialist, nuclear-armed republic and the great Workers’ Party of Korea!”

09:28

'Grave breach of UN resolutions'

Foreign Secretary Phillip Hammond told the Daily Telegraph: “If a nuclear device has been detonated by North Korea, this is a grave breach of UN Security Council resolutions and a provocation which I condemn without reservation.

“It underlines the very real threat that North Korea represents to regional and international security.

“We will be working with other UN Security Council members to ensure the international community responds urgently and decisively to this latest activity.”

“I have discussed this matter today in Beijing with my Chinese counterpart, State Councillor Yang Jiechi, and we have agreed to work with other members of the UN Security Council towards a robust international response.”